Michael: sorry to hear about your experience. I work at Comcast HQ; we actually are quite focused on fixing our customer service / customer experience problems. PM me if you have outstanding concerns.
Regarding your issue:
Looks like you figured it out -- but if you can get to Comcast.net and login to Email (SmartZone), you can click on the "Voice" tab, then "Call Manager" (sub-menu item). Here you can set call forwarding preferences remotely.
If you have an iPhone, you can download the Comcast app for free. This also supports call forwarding management. Touch "Digital Voice" from the main menu, then in the lower right corner touch the phone icon. Here you can turn on forwarding.
Again, PM me if I can help with anything else.
Back to the funnies...